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Microgravity effect on the vestibulo-ocular reflex is dependent on otolith and vision contributions
1Laboratory of Motor Control, Institute of Physiology, Bulgarian Academy of Sciences, Sofia, Bulgaria.
Aviation, Space, and Environmental Medicine
|October 1, 1996
Summary
Microgravity alters the vestibulo-ocular reflex (VOR), impacting eye movements during head turns. The otoliths
Area of Science:
- Vestibular Neuroscience
- Space Physiology
Background:
- Investigating the influence of microgravity on the vestibulo-ocular reflex (VOR).
- Examining the otolith's contribution to VOR in the absence of gravity.
Purpose of the Study:
- To determine how microgravity affects horizontal and vertical VOR.
- To understand the otolith's role in VOR without gravitational input.
Main Methods:
- Studied six cosmonauts during and after space missions.
- Elicited VOR using active yaw and roll head movements at 0.2 Hz.
Main Results:
- Observed central VOR reprogramming and non-specific microgravity effects on horizontal VOR.
- Noted new horizontal and vertical VOR during roll head movements in microgravity.
- Documented unidirectional downward eye movements in a long-term spaceflight participant, likely due to absent otolith stimulation.
Conclusions:
- A specific microgravity effect on VOR was identified during roll head movements, highlighting semicircular canal-otolith interaction.
- The stability of VOR patterns during readaptation depended on microgravity exposure duration.
- Vision appears to dominate visual-vestibular interactions when "space" and "terrestrial" sensory patterns conflict.